Luke Boswell (Nov 22 2024 at 22:22): Luke Boswell (Nov 22 2024 at 22:22):@Oskar Hahn left some helpful comments on the zig template upgrade, one of which I found interesting and wanted to ask about.
Currently, libc is also needed for the inline-expect. But there is the plan to solve inline-expect the same way then dbg. If this is implemented, then a zig-roc-binary would not need libc and could be statically linked.
Do we have plans/any issues to track this work?
I assume the idea is that the platform provides a roc_expect effect that gets called when we hit an inline expectation.
Brendan Hansknecht (Nov 22 2024 at 23:30):Yes
Brendan Hansknecht (Nov 22 2024 at 23:30):I filed an issue for it a long while back
Brendan Hansknecht (Nov 22 2024 at 23:33):https://github.com/roc-lang/roc/issues/6930
Luke Boswell (Nov 23 2024 at 01:11):Just looking at that change... it looks like we should at least put the effect into basic-cli and basic-webserver etc so it's ready for this change in future, even if it's not used currently.
Update all platforms to have
roc_expect_failedwith the api:fn roc_expect_failed(loc: *RocStr, src: *RocStr, variables: *RocList<{name: RocStr, value: RocStr}>).
Are we happy with this name still? I kind of like the idea of just roc_expect but don't mind the longer version.
Luke Boswell (Nov 23 2024 at 01:13):Original proposal https://roc.zulipchat.com/#narrow/channel/395097-compiler-development/topic/roc_expect_failed/near/418463775
Richard Feldman (Nov 23 2024 at 01:13):I think it's clearer with the longer name - like this only gets called when an expectation fails
Luke Boswell (Nov 23 2024 at 01:15):I'm thinking I'll add it into the purity inference PR... unless you would prefer a separate PR for it?
Luke Boswell (Nov 23 2024 at 01:15):That will save merge conflicts when we land that
Luke Boswell (Nov 23 2024 at 01:24):https://github.com/roc-lang/basic-cli/pull/271
Brendan Hansknecht (Nov 23 2024 at 01:50):Ad it to purity inference?
Luke Boswell (Nov 23 2024 at 01:51):^^^ this PR is based of the purity-inference branch in basic-cli and is a PR to merge back into that.
Luke Boswell (Nov 23 2024 at 01:51):As opposed to the main branch
Brendan Hansknecht (Nov 23 2024 at 01:52):I'm a little lost, no one has done the work in the compiler to use expect this way
Brendan Hansknecht (Nov 23 2024 at 01:52):I think that will be a medium sized lift. More work than debug was
Brendan Hansknecht (Nov 23 2024 at 01:52):I wouldn't expect it to be ready for a while.
Luke Boswell (Nov 23 2024 at 01:52):Yeah, but adding into the host means that when we do it won't be a breaking change/easier to test.
Luke Boswell (Nov 23 2024 at 01:53):I'm starting to think the dbg, expect and passed in allocators is my highest priority over new syntax or build pipeline stuff
Brendan Hansknecht (Nov 23 2024 at 01:53):Oh, just adding the effect to the host now ....sure, though wouldn't be surprised if the API changes while implementing, but could add it
Luke Boswell (Nov 23 2024 at 01:53):It just has a big impact on the platform development, and there are things I want to do with roc-ray and this stuff is really holding us back
Brendan Hansknecht (Nov 23 2024 at 01:53):Got it
Brendan Hansknecht (Nov 23 2024 at 01:53):Makes sense
Luke Boswell (Nov 23 2024 at 01:54):Yeah, I hope the API doesn't change too much... this may be too premature
Luke Boswell (Nov 23 2024 at 01:55):I think that will be a medium sized lift. More work than debug was
Where in the compiler is all this work? Is it mostly backend/code gen related?
Brendan Hansknecht (Nov 23 2024 at 03:49):Looking at the linked PRs would help
Brendan Hansknecht (Nov 23 2024 at 03:50):Some of it is in ripping out a lot of test infra and runtime loading that deals with expect today
Brendan Hansknecht (Nov 23 2024 at 03:50):Some is in the pipeline of how expect is lowered
Brendan Hansknecht (Nov 23 2024 at 03:51):Code gen is where this bottoms out but should be relatively minimal
Oskar Hahn (Nov 23 2024 at 07:14):When you are talking about the API of these functions:
The current API for dbg is:
fn roc_dbg(loc: *str.RocStr, msg: *str.RocStr, src: *str.RocStr) callconv(.C) void
When I remember correctly, then the third argument was added in December 2023. The idea was, that it was added as a third argument, so it is backward compatible. But the order should change after AoC2023.
So I think some API changes are very likely and therefore it is not helpful to add the functions to the platform at the moment.
Oskar Hahn (Nov 23 2024 at 11:41):I tired to remove the stuff needed for the inline expect from my aoc-platform and I can confirm, that without it, libc is not needed and you get a statically linked binary:
$ roc build days/day01.roc
0 errors and 0 warnings found in 307 ms
while successfully building:
days/day01
$ ldd days/day01
statically linked
What is needed for inline expect today? Why does it need libc?
Oskar Hahn (Nov 23 2024 at 16:42):As far as I know, it needs shm_open, mmap and getppid
Oskar Hahn (Nov 23 2024 at 16:45):Yes, if I do not export roc_getppid, roc_mmap or roc_shm_open, inline expect does not work. And I don't know how to implement them manually.
Brendan Hansknecht (Nov 23 2024 at 17:15):Ah
Brendan Hansknecht (Nov 23 2024 at 17:16):Yeah I guess those need libc or direct os system calls....but libc is the easy way
Brendan Hansknecht (Nov 23 2024 at 17:16):Forgot about those primitives. Yeah, they would get removed with these changes
Luke Boswell (Nov 28 2024 at 06:29):Made a start on this change https://github.com/roc-lang/roc/pull/7256
I have no idea how big this change will be... but figured I'd give it a go.
So far I've got to this point... looks to be calling my low level (from llvm) and passing in some values I hardcoded in Can. I need to figure out how to thread the source and location in from Parse to Can, it looks a bit different than how Dbg does things.
Also, no idea why this "traps"... probably need to run on linux and/or use a debugger to figure that out.
$ cargo run -- test examples/platform-switching/rocLovesZig.roc
Finished dev [unoptimized + debuginfo] target(s) in 0.58s
Running `target/debug/roc test examples/platform-switching/rocLovesZig.roc`
[HOW DO WE GET SOURCE TO CAN?] HOW DO WE GET SOURCE TO CAN? = TODO IMPLEMENT ME!
Trace/BPT trap: 5
Last updated: Jul 26 2025 at 12:14 UTC